Thermographic reproduction paper and method of using



March 16, 1965 H. BRIGGS ETAL 3,174,038

THERMOGRAPHIC REPRODUCTION PAPER AND METHOD OF USING Filed June 18, 1962 FIG! REDUCING CARBOHYDRATE O-DIANISIDINE ACID CAT- 4 ssxeu TO BE COPIED DESIGN TO BE COPIED l I 4 MASTER 5 L\ I\ yREDucmG CARBOHYDRATE II/ll. 0/111 F71 l/A\2 ELQIAIVISIDINE ACID CAT- I i u l 3 BASE VISIBLE IMAGE INVENTORS HARTWELL L. BRIGGS CORNELIUS B. LAWYER GEORGE C. I-IUETT ATT'YS United States Patent 3,17 4,038 THERMOGRAPHIC REPRGDUCTION PAPER AND METHOD OF USING Hartwell L. Briggs, Cornelius B. Lawyer, and George C. Huett, Chicago, IlL, assignors to Eugene Dietzgen Co.,

Chicago, 111., a corporation of Delaware Filed June 18, 1962, Ser. No. 293,030 21 Claims. (Cl. 25G65) The subject invention relates to the production of thermognaphic paper. More particularly, the present invention is directed to improved copying materials which are capable of producing a facsimile copy by means of radiant energy.

In the past several years, various types of copy paper have been developed which produce a facsimile copy when exposed to radiant energy such as infrared light beneath graphic subject matter set forth on an original. A typical thermographic process is described in the patent to Miller, US. 2,740,896. As is disclosed in this patent, carbon inks and certain other marking means absorb radiant energy from infrared bulbs creating heat. This energy is transferred to a sensitized sheet of copy paper in contact with the original causing the formation of duplicate characters.

A wide variety of materials have been used as color producing bodies in coating copy paper. In heat develop- -able diazotype reproduction systems, for example, copy paper is coated with a diazo compound, a coupler, and a compound which produces an alkaline reaction when heated. In other systems such materials as metal stearates, sodium behenate, nickel acetate, etc. have been used as components of the color producing coating.

It has been found that compositions of the above type often have disadvantages, especially where the copy paper is to be used on a commercial basis. Such materials, for example, often tend to be unstable both prior to development and subsequent to the formation of the facsimile, which facsimiles cannot be used as intermediates for producing other copies. Additionally, many of the known coating compositions are relatively expensive and are difficult to handle on a commercial scale.

A novel thermographic process is described in copending application Serial Number 181,091 which was filed on March 20, 1962. This application covers a theme-graphic process in which either the cellulose in paper or carbohydrates coated on a suitable base are treated so as to produce a color image by means of radiant energy transferred from the characters of an original to the copy sheet. In the embodiment of the process wherein paper is coated with a solution of carbohydrate such as lactose, glucose, mannose, etc, certain acids are incorporated in the coating along with stabilizing agents. The disclosure of application Serial No. 181,091 is considered to be a part of the subject disclosure.

It is an object of the present invention to provide an improvement in the plrocess described in application Serial No. 181,091 wherein the coating composition includes a reducing carbohydrate.

It is a further object of the invention to provide a new class of heat reactive copy papers which can be used to make reproduction of originals printed on one or both sides.

Another object of the invention is to provide copy paper which will produce accurate and clear facsimiles.

Still another object is to provide copy material which can be used to produce read out copies or intermediates regardless of whether the copy material is coated on one or both sides.

Another object is to provide copy material which can be used to reproduce originals by a front printing techmque.

3,l74,h38 Patented Mar. 16, 1965 ice Still another object is to provide copy paper which can be used to produce originals by a heat transmission technique.

A still further object of the invention is to provide copy paper which can be used to produce facsimiles having Well defined characters without causing the blurring of surrounding background areas.

Other objects will become apparent to those skilled in the art from the following detailed description of the invention.

In general, the present invention comprises the discovery that the addition of certain compounds to the coating composition disclosed in application Serial No. 181,091 provides a highly satisfactory thermographic reproduction system. Depending upon the particular compound selected, the color of the print will vary from yellow-green to brown-yellow to brown to brown-violet to black prints. The compounds which are added to the reducing carbohydrate composition disclosed in the aforementioned application include o-dianisidine, 2,7-diaminofluorine, triphenyltetrazolium choride, dinitroacetanelide, silver nitrate, and bismuth nitrate. In the case of o-dianisidine and 2,7-diaminofluorine an acid catalyst is used in the composition. With respect to triphenyltetrazolium chloride, dinitroacetaneide, silver nitrate, and bismuth nitrate, a suitable base is added to the composition rather than the acid.

In carrying out the process, paper or another suitable base is coated with a sensitizing solution containing reducing carbohydrate, one of the coreacting compounds disclosed above, an acid or base, and a stabilizing agent, etc. The sensitized paper is then placed in contact with an original which can be printed on one or both sides. The resultant sandwich is subjected to radiant energy such as visible light in the orange and red spectral zones or invisible infrared radiation. If a front printing technique is used the radiant energy passes through the heat sensitive copy material whereupon it is absorbed by the characters of the original producing heat which is transmitted to the reproduction material. If a direct transmission technique is used the radiant energy is focused on the original (printed only on one side), the characters of which absorb the energy, convert it to heat, and cause the formation on the copy material of characters duplicat ing the characters of the original. The heat transferred to the copy material initiates a chemical reaction on the treated sheet leading to the formation of highly colored bodies.

The reducing carbohydrates which can be used in the process include monosaccharides such as galactose, glucose, mannose, gulose, dextrose, etc; oligosaccharides such as maltose, lactose, cellobiose, etc; polysaccharides, cellulose, starch, dextrin, pentoses such as arabinose, ribose, xylose, and lyxose, etc., and ketos sugars such as fructose. As a replacement for the reducing carbohydrate in the above system, an aldehyde, a ketone, or an aldehyde-forming compound can be added to the coating composition.

Both aliphatic and aromatic aldehydes and ketones can be used in the invention. It is essential, however, that the aldehydes and ketones have a boiling point of 50 C. or higher. Among the suitable aliphatic aldehydes are those containing from 3 to 8 carbon atoms, such as glyoXal, adipaldehyde, a-hydroxyadipaldehyde, n-butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, trimethylacetaldehyde, n-caproic aldehyde, heptaldehyde, and n-caprylic aldehyde. Suitable aliphatic ketones would include those containing from 4 to 11 carbon atoms, such as dihydroxy acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, me'thyl sec-butyl ketone, ethyl propyl ketone, ethyl isopropyl ketone, dipropyl ketone, methyl amyl ketone, dibutyl ketone, and diamyl ketone. Suitable aromatic aldehydes and ketones would include benzaldehyde, ortho-, metaand para-toluic aldehyde, ortho-, metaand para-hydroxy benzaldehyde, ortho-, me'ta-, and p'ara-chlorobenzaldehyde, orthoand metanitrobenzaldehyde, a-naphthaldehyde, phenylacetaldehyde, vanillin, anisaldehyde, salicylic aldehyde, acetophenone and benzophenone. Among the compounds which form aldehydes under the conditions of the reaction which can be used in the process are eugenol, isoeugenol, anethole, and salfrole.

As was pointed out above, a compound selected from the group consisting of o-dianisidine, 2,7-diaminofluorine, triphenyltetrazolium chloride, dinitroace'tanelide, silver nitrate and bismuth nitrate is added to a solvent solution containing either a reducing carbohydrate or an aldehyde, ketone, or aldehyde-forming composition of the type described above as well as an acid or base and a stabilizing agent. These compounds produce a color yielding reaction when subjected to heat. Suitable solvents include lower alcohols such as ethanol,'isopropanol, butanol, ethyl Cellosolve, benzene, toluene, etc. The solution is applied to a suitable base such as paper, Mylar, etc. On drying, a tackfree, highly sensitive base is obtain'ed.

The invention is illustrated in the attached schematic drawing in which: 7

FIGURE 1 is an enlarged fragmentary cross-section of a sheet of reproduction paper embodying the invention and shown in print making relation to a cross-section of the original to be copied; and

FIGURE 2 is an enlarged fragmentary cross-section of a sheet of reproduction material which illustrates a modified. process which may be practiced in carrying out the subject invention. 7

The reproductionor copymaterial 1 illustrated in the drawing is composed of a sensitive layer 2 of a base 3. The sensitive layer 2 consists of paper which has been treated with a solution containing a reducing type carbohydrate or an aldehyde, ltetone, or aldehyde-producing compound, .as well as one of the modifying compounds described above. The solution also contains either an acid'or a base catalyst and a stabilizing agent.

FIG. 1 illustrates a front printing process which constitutes a preferred embodiment of the invention. In this process, the sheet of reproduction material 1 containing sensitized layer 2 on base 3 is superimposed on master or original 4 forming an exposure sandwich S. The master consists of a sheet or base layer 5 of paper or graphically markable sheet material containing a design, drawing, written or typed character 6 to be copied. As is indicated in the figure, character 6 can be on both sides of the sheet in the front printing system. Radiations Re such as visible light in the orange and red spectral zones as well as invisible infrared radiation is produced by radiation source 7. The radiations Re pass through the copy material 1 and strike the face surface 8 of original 4. Radiations striking character 6 of master 4 are converted to heat which is conducted as indicated at H to the sensitive layer 2 of the reproduction material. An image 6" is produced which duplicates original character 6. Radiations that are not absorbed either are reflected as shown at 9 or are transmitted through "the materials. Where the original is printed on both sides, the unabsorbed radiations are reflected by adjusting radiations Re. .The radiations are focused on the surface of the copy paper in an elongated zone normal to the face of the sandwich, while the sandwich moves with respect tosaid zone in the direction of the arrow. If it is desiredfthe base 3 can be coated or sensitized on both sides. Under these circumstances, the print would appear both on the front and the back of the copy sheet.

In FIG. 2 a back printing method is described in which reproduction material 1 is beneath master or original 4. Once again, the master consists of a sheet or base layer 5 of paper or graphically markable sheet material containing a design, drawing, written or typed character 6 to be copied. The master is superimposed on the sheet of reproduction material 1 to form an exposure sandwich S. Radiations Re such as visible light in the orange and red spectral zones as well as invisible infrared radiation is produced by radiation source 7. The radiant energy source 7 preferably is arranged so as to scan the original and copy materials. Radiations Re are concentrated and focused on the face surface 8 of the original in an elongated zone normal to the face of the drawing, while the sandwich moves with respect to said zone in the direction of the arrow. As each portion of the sandwich passes through the focal zone, radiations are absorbed by the design area 6 and are converted to heat, which, as shown at H, is conducted through the base 5 of the original 4, to the sensitive layer 2 of tlie copy material. The heat produces a color-forming reaction in the sensitive layer which produces duplicate characters 6".

The radiations which are not absorbed by character 6 are reflected as is illustrated at 9, or they may be transmitted through base 5 of the original depending upon the materials used. These rays normally do not affect the reproduction if the original contains a design only on its face surface.

It is preferred that a stabilizing agent be added to the subject treating solution. Materials that can be used as stabilizing agents include urea, biuret; triethanolamine, triphenylphosphate, tribu'tylphosphate, tricresylphosphate,

symmetrical dimethyl urea, symmetrical diphenyl urea,

invention.

Example I In this example, reproduction paper having a visible light transmission characteristic of greater than 30% was treated with a composition made up of the following ingredients:

' G. O-dianisidine 2.0 Sulfo salicylic acid 2.0 D+glucose 3.0 Isopropanol 40.0 Water 10.0

The solution was applied to the paper with a solution-wet roller, although other means could be used such as spraying, kiss coating, slot fountain, etc. After the excess was removedthe paper was dried in a drying o-ven held at 70 C. for about seconds and was superimposed on an original containing typed graphic characters. The resultant sandwich was placed beneath an infrared bulb whereby the characters on the original were reproduced on the copy paper by a front printing system such as is illustrated in- FIG. 1 of the drawing. An excellent reproduction of the original was obtained by this method. The characters of the reproduction were yellow-green in color. The copies which were obtained could be used as intermediates or read out copies.

Example II In this example, reproduction material was treated with a composition made up of the following ingredients:

Thiourea 0.1

In this test the solution again was applied to the paper with a solution-wet roller. After the excess had been removed, the paper was dried in an oven. A tackfree, highly heatsensitive base was obtained. The treated paper was placed in sandwich relationship with a superimposed original having typed graphic characters which were black in color. The sandwich was placed beneath an infrared bu lb where by radiation from the bulb was absorbed by the graphic characters on the original. Heat was transferred to the copy paper which caused a reaction to occur on the treated base forming characters which duplicated the characters of the original. The reproduction had good contrast and was satisfactory in all respects. The characters of the copy print were red-brown in color.

Example 111 In this example, cellulosic reproduction paper was treated with a composition made up of the following in- The solution again was applied to the paper with a solution-wet ro'ller. After the excess was removed and the paper was dried in an oven in a manner described in EX- ample I, the treated copy paper was superimposed on an original containing typed graphic characters. The resultant sandwich was placed beneath an infrared bulb whereby the characters on the original were reproduced on the copy paper by a front printing system which is described in connection with FIG. 1 of the drawing. Once again, an excellent reproduction of the original was obtained by this method. The characters of the reproduction were black in color. The substitution of bismuth nitrate for silver nitrate in the above formulation produces comparable results.

In carrying out the subject process it is not necessary to use binder resins to hold the applied coatings to the surface of the base. If it is desired, however, water-soluble or water-emulsifiable polymers can be used for this purpose. Examples of such polymers would include polyvinyl acetates, acrylic type polymers, phenol-fornmaldehyde resins, water-soluble alkyd resins, etc.

As was pointed out above, a suitable acid should be used as a catalyst in the formulation containing o-dianisidine or 2,7-diaminofluorine, whereas suitable bases such as NaOH, sodium carbonate, ammonium carbonate, etc., are used in connection with formulations containing triphenyltetrazolium chloride, dinitroacetanelide, silver nitrate and bismuth nitrate. It is preferred that the acids used in connection with o-dianisidine and 2,7-diaminofluorine are organic acids having an ionization constant varying from that of citric acid to that of meta-benzene disulfonic acid.

The temperature of the paper in the areas of the polymerization reaction will vary from about 240 F. to about 360 F. The temperature required to produce a satisfactory print, of course, will depend upon the printing speed, the voltage across the lamp source, etc. In most instances, the paper need be exposed to the radiation for only a brief period of time, for example, from 0.05 secend up to about 3 seconds, and preferably from 0.1 to 0.5 second.

The quantity of modifying agent that is used in the coating solution can vary widely. It has been found that from about 1 to about 20 grams of modifying agent, such as o-dianisidine, per 100 grams of organic solvent or organic solvent plus water is satisfactory in most instances. The preferred range of modifying agent is from about 2 6 to about 10 grams per grams of solvent or solvent and water.

The amount of reducing type carbohydrate that is used in the coating solution can also vary from about 1 to about 20 grams of carbohydrate per 100 grams of water or organic solvent plus water. The preferred carbohydrate range is from about 2 to about 10 grams per 100 grams of solvent. A comparable amount of aldehyde, ketone, or aldehyde-forming compound can be used in the process.

Obviously many modifications and variations of the invention tas hcreinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing a catalyst, a material selected from the group consisting of o-dianisidine, 2,7-diaminofiuorine, triphenyltetrazolium chloride, dinitroacetanelide, silver nitrate and bismuth nitrate and a composition selected from the group consisting of a reducing type carbohydrate, an aldehyde, a icetone, eugenol, isoeugenol, anathole and saffrole, said aldehyde and said ketone having a boiling point above 50 C. and thereafter irradiating said original with heat producing radiations to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

2. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing o-dianisidine, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saifroie, said aldehyde and said ketone having a boiling point above 50 C. and a catalyzing acid, and thereafter irradiating said original with heat producing radiations to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

3. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing triphenyltetrazolium chloride, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anatho-le and saifrole, said aldehyde and said ketone having a boiling point above 50 C. and a base, and thereafter irradiating said original with heat producing radiations to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

4. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing dinitroacetanelide, a compound selectfrom the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and safirole, said aldehyde and said ketone having a boiling point above 50 C. and a base, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

5. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing silver nitrate, a compound selected from the group consisting of a reducing type carbohydrate, an'aldehyde, a ketone, eugenol, isoeugenol, anathole and saifrole, said aldehyde and said ketone having a boiling point above 50 C. and a base, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a reaction in the areas of said supported layer registering. with said radiation absorbing areas, whereby said original is visibly reproduced.

6. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing bismuth nitrate, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saifrole, said aldehyde and said ketone having a boiling point above 50 C. and a base, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

7. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing 2,7-diaminofluorine, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saifrole, said aldehyde and said ketone having a boiling point above 50 C. and a catalyzing acid, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a reactionin the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

8. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing o-dianisidine, a reducing type carbohydrate, and a catalyzing organic acid, said acid having an ionization constant varying from that of citric acid to that of meta-benzene disulfonic acid and thereafter irradiating said original with heat'producing radiations to increase 'the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a. reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

9. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing triphenyltetrazolium chloride, a reducing type carbohydrate, and a base selected from the group consisting of sodium hydroxide, sodium carbonate andammonium carbonate, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to elfect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly'reproduced.

10. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing dinitroacetanelide, a reducing type carbohydrate, and a base selected from the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

11. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing silver nitrate, a reducing type carbohydrate, and a base selected from the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate, and thereafter irradiating said original with heat producing radiations to increase the tempera ture of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to elfect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

12. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in contact with a supported layer of a visibly heat-sensitive composition, said composition containing bismuth nitrate, a reducing type carbohydrate, and a base selected from the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate, and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to effect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

13. A process for graphically producing an original which comprises: placing an original having preferential radiation absorbing areas in' contact with a supported layer of a visibly heat-sensitive composition, said composition containing 2,'7-diaminofiuorine, a reducing type carbohydrate, and a catalyzing organic acid, said acid having an ionization constant varying from that of citric acid to that of meta-benzene disulfonic acid and thereafter irradiating said original with heat producing radiations to increase the temperature of said preferential radiation absorbing areas to from about 240 F. to about 360 F. and to efifect a reaction in the areas of said supported layer registering with said radiation absorbing areas, whereby said original is visibly reproduced.

l4. Reproduction material which comprises: a supported layer of a heat-sensitive composition, said composition containing. o-dianisidine, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saffrole, said aldehyde and said ketone having a boiling point above 50 C. and an acid catalyst.

15. Reproduction material which comprises: a supported layer of a heat-sensitive composition, said composition containing triphenyltetrazolium chloride, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saffrole, said aldehyde and said ketone having a' boiling point above 50 C. and a basic catalyst selected from the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate.

16. Reproduction material which comprises: a supported layer of a heat-sensitive composition, said composition containing dinitroacetanelide, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saffrole, said aldehyde and said ketone having a boiling point above 50 C. and a basic catalyst.

17. Reproduction material which comprises: a supported layer of a heat-sensitive composition, said composition containing 2,7-diaminoiluorine, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and safirole, said aldehyde and said ketone having a boiling point above 50 C. and an acid catalyst.

18. Reproduction material which comprises: a supported layer of a heat-sensitive composition, said composition containing bismuth nitrate, a compound selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and saifrole, said aldehyde and said ketone having a boiling point above 50 C. and a basic catalyst selected irom the group consisting of sodium hydroxide, sodium carbonate and ammonium carbonate.

19. A process for producing a thermally developable copy sheet which comprises: applying to a support men her a solvent solution containing a modifying agent selected from the group consisting of o-dianisidine, 2,7- diarninofiuorine, triphenyl-tetrazolium chloride, dinitroacetanelide, silver nitrate, and bismuth nitrate, containing a second material selected from the group consisting of a reducing type carbohydrate, an aldehyde, a ketone, eugenol, isoeugenol, anathole and satfrole, said aldehyde and said ketone having a boiling point above 50 C., and containing a catalyst, the amount of said modifying agent being from about 2 to about 10 grams per 100 grams of solvent, and the amount of said second material being from about 2 to about 10 grams per 100 grams of solvent; and thereafter removing the volatile substituents from said solvent solution whereby a heat-sensitive coating is formed on said support member.

20. A process for producing a thermally developable copy sheet which comprises: applying to a support member a solvent solution containing o-dianisidine, a reducing type carbohydrate and an organic acid catalyst, said catalyst having an ionization constant varying from that of citric acid to that of meta-benzene disulfonic acid, the amount of o-dianisidine being from about 2 to about 10 grams per grams of solvent, and the amount of reducing type carbohydrate being from about 2 to about 10 grams per 100 grams of solvent; and thereafter removing the volatile substituents from said solvent solu-' tion whereby a heat-sensitive coating is formed on said support member.

21. A process for producing a thermally developable copy sheet which comprises: applying to a support member a solvent solution containing triphenyltetrazolium chloride, glyoxal, and a basic catalyst selected from the group consisting of sodium hydroxide, sodium carbonate, and ammonium carbonate, the amount of triphenyltetrazolium chloride being from about 2 to about 10 grams per 100 grams of solvent, and the amount of glyoxal being from about 2 to about 10 grams per 100 grams of solvent; and thereafter removing the volatile substituents from said solvent solution whereby a heat-sensitive coating is formed on said support member.

References Cited by the Examiner UNITED STATES PATENTS 1,844,199 2/32 Bicknell et al 1l736.8 XR 1,944,293 1/34 Martinez.

2,625,494 l/53 Morrison 1l7-36.8 XR 2,844,733 7/58 Miller et a1. 117-36.8 XR 2,897,090 7/59 Van Dam 117-36.8 XR 2,910,377 10/59 Owen 11736.9 3,024,362 3/62 Sus et a1 117-36.8 XR

OTHER REFERENCES Wein: Metallizing Non-Conductors, 1944 pp. 29-39, Met. Ind. Pub. Co., New York.

RICHARD D. NEVIUS, Primary Examiner. MURRAY KATZ, Examiner. 

1. A PROCESS FOR GRAPHICALLY PRODUCING AN ORGINAL WHICH COMPRISES: PLACING AN ORIGINAL HAVING PREFERENTIAL RADIATION ABSORBING AREAS IN CONTACT WITH A SUPPORTED LAYER OF A VISIBLY HEAT-SENSITIVE COMPOSITION, SAID COMPOSITON CONTAINING A CATALYST, A MATERIAL SELECTED FROM THE GROUP CONSISTING OF O-DIANISIDINE, 2,7-DIAMINOFLUORINE, TRIPHENYLTETRAZOLIUM CHLORIDE, DINITROACETANELIDE, SILVER NITRATE AND BISMUTH NITRATE AND A COMPOSITION SELECTED FROM THE GROUP CONSISTING OF A REDUCING TYPE CARBOHYDRATE, AN ALDEHYDE, A KETONE, EUGENOL, ISOEUGENOL, ANATHOLE AND SAFFROLE, SAID ALDEHYDE AND SAID KETONE HAVING A BOILING POINT ABOVE 50*C. AND TEHREAFTER IRADIATING SAID ORIGINAL WITH HEAT PRODUCING RADIATIONSTO EFFECT A REACTION IN THE AREAS OF SAID SUPPORTED LAYER REGISTERING WITH SAID READIATION ABSORBING AREAS, WHEREBY SAID ORIGINAL IS VISIBLY REPRODUCED. 